The present invention relates to an improvement in a bearing apparatus for a rotary machine having a horizontal rotating shaft, and more particularly, to an improvement in a bearing apparatus in which lubricating oil is contained in a lubricating oil tank and is automatically supplied to a bearing by means of the rotation of the horizontal rotating shaft.
Hitherto, in automatically oil supplied type bearing apparatus which have been applied to the rotary machines, for example, a motor having a horizontal main shaft, a system has been employed in which an oil ring, an oil disk, a viscous pump or the like is provided in the bearing or in the vicinity of the bearing and the lubricating oil is picked up from the lubricating oil tank and supplied to the bearing by means of the rotation of the main shaft. In that system, the lubricating oil which has been supplied to the bearing and contributed to the lubrication of the bearing becomes higher in temperature due to the shearing and friction action and falls from the both ends of the bearing onto a surface of the lubricating oil in the lubricating oil tank. Therefore, the hot oil cannot mix with cold lubricating oil remaining adjacent to side walls and a bottom wall of the lubricating oil tank and is accumulated only in the upper portion of the lubricating oil in the tank. As a result, there results a problem that the radiation of the heat cannot be effectively performed.
In view of the foregoing, a bearing is disclosed in Japanese Utility Model Laid-Open Publication No. 53-123346 and another in Japanese Utility Model Laid-Open Publication No. 53-115246 which attempt to obviate this problem.
The bearing disclosed in Japanese Utility Model Laid-Open Publication No. 53-123346 comprises: a lubricating oil receiver disposed beneath a bearing; a plurality of partition members that stand on an inside of a bottom wall of a lubricating oil tank; and heat radiation fins that are disposed on an outer surface of the bottom wall of the lubricating oil tank. Thus, the lubricating oil discharged from the bearing is collected by the lubricating oil receiver in a portion of the lubricating oil tank which is opposite to a lubricating oil supply device. The thus collected lubricating oil then meanders in the lubricating oil tank, and is then picked up by the lubricating oil supply device again. The heat of the lubricating oil is radiated outside by virtue of the radiation fins disposed on an outer surface of the bottom wall of the lubricating oil tank while lubricating oil is meandering in this way. In the device described above, heat is radiated solely from the bottom wall of the lubricating oil tank. In addition, since the flow generated by virtue of the operation of the lubricating oil supply device is extremely limited, the high temperature lubricating oil discharged from the bearing readily gathers in the portion of the lubricating oil tank at the position opposite to the lubricating oil supply device. As a result, heat radiation from the lubricating oil tank cannot be performed efficiently.
The bearing apparatus disclosed in Japanese Utility Model laid-Open Publication No. 53-115246 is structured in such a manner that fans are provided on the rotational shaft, fins are attached to and an air duct is provided on the outer surface of the bearing, and the lubricating oil tank is divided into two sections that are communicated by a cooling pipe. This device is designed to improve the cooling effect by allowing the lubricating oil in the lubricating oil tank be cooled by the fan attached to the rotational shaft and supplying air forcedly and directly to the outer surface of the bearing. However, this involves certain economic disadvantages since the windage loss attributable to the fans is considerable and the structure of the device becomes too complicated.
An additional proposal has been made with a view to improving the cooling effect by inserting a heat pipe in the lubricating oil tank. However, an adequate cooling performance can only be obtained with this device, if its size is considerably enlarged, thus leading to economic disadvantages.